As others have said, he’ll probably be that Bruce Brown replacement. Here’s the pros and cons in my mind:

Pros:

• Cuts well and can get to the rim. Great for Jokic who should almost always see him.
• Veteran who can challenge Murray when Murray is playing like ass, especially in the regular season. Should also be a veteran presence for the young bench (Watson, Strawther, Picket)
• Offers flexible lineups. Reggie Jackson didn’t offer much when Murray was also on the floor. Russ’s versatility with speed and rim running could make him work alongside Murray.
• Ball Handling - Denver is desperate for a ball handler who can supplement Murray out there. While Russ is no better than Reggie in this regard, he’s much better than Picket, Braun, or Strawther.
• Defense?… not really a pro for him but Reggie Jackson was terrible out there and Westbrook is at least average to above average.

Cons:

• Floor spacing. His poor jump shots could really limit his value playing alongside Jokic. Aaron Gordon has already created this problem that teams took advantage of in the playoffs. Westbrook would exacerbate that.
• Culture. Westbrook has had locker room problems a few places he’s gone. Nuggets pride themselves on everyone being bought in. If he can’t buy in to his role, could cause issues.